An input device is an essential device for people in the modern society. For example, a conventional keyboard is one of the common input devices. The conventional keyboard comprises plural keys. When one of the keys is pressed, a command is inputted through the keyboard. Generally, the conventional keyboard has many types according to the designs of generating the key signal. For example, a force-sensitive input device is one type of the conventional keyboard. Moreover, one key of the force-sensitive input device is designed to sense the magnitude of the pressing force. According to the magnitude of the pressing force, a corresponding function is triggered. For example, in case that a force of 0˜30 grams is applied to the key, the key is pressed down to a shallower position. Consequently, a first predetermined function is triggered. In case that a force of 30˜60 grams is applied to the key, the key is pressed down to a deeper position. Consequently, a second predetermined function is triggered. That is, when the pressing force with the first magnitude or the pressing force with the second magnitude is selectively applied to the same key, the corresponding predetermined function is enabled.
However, the conventional force-sensitive input device still has some drawbacks. For example, while the key is pressed by the user, it is difficult for the use to finely perceive the pressing force that is exerted by the user. That is, the user cannot actually trigger the desired function. In some situations, the undesired function is erroneously triggered. The use of the force-sensitive input device usually perplexes the user.
Therefore, there is a need of providing an improved force-sensitive input device in order to overcome the above drawbacks.